Positional tracking system and method

ABSTRACT

A position tracking system has a laser transmitter, a control tracker and a layout indicator. The laser transmitter has a laser for emitting a laser beam, a controller controlling the laser, and a motor for rotating the emitted laser beam. The control tracker has a housing, at least two photo diodes disposed on the housing, and a laser assembly for generating a beam to be projected unto a surface. The layout indicator has a housing, and at least two photo diodes disposed on the housing. A network server communicates with at least one of the laser transmitter, the control tracker and the layout indicator.

CROSS-REFERENCE TO RELATED APPLICATIONS

The following application derives priority from U.S. Application Ser.No. 62/676,375, filed on May 25, 2018 and titled “POSITIONAL TRACKINGSYSTEM AND METHOD”, U.S. Application Ser. No. 62/726,679, filed on Sep.4, 2018 and titled “POSITIONAL TRACKING SYSTEM AND METHOD”, and U.S.Application Ser. No. 62/757,840, filed on Nov. 9, 2018 and titled“POSITIONAL TRACKING SYSTEM AND METHOD”, which are incorporated hereinby reference.

FIELD

The present invention relates to a positional tracking system andmethod, and more particularly to optics-based positional trackingsystems and methods for locating objects and locations in a constructionjobsite.

BACKGROUND

It is well known to use laser measuring systems to locate differentpoints throughout a construction jobsite. One established lasermeasuring technique and measuring system utilizes a projection of alaser beam by a rotary irradiation (e.g., a laser transmitter) for thepurpose of forming a horizontal reference plane or a reference planetilted with respect to the horizontal reference plane at a predeterminedangle and by which it is possible to measure a position by using thetransmitted laser beam. In this way, the applicable measuringinstruments measure the coordinates of a point by sending a laser beamto the point. The laser beam may impinge directly on the point or mayimpinge on a retro reflector target that is contact with the point. Themeasuring instruments determine the coordinates of the point bymeasuring the distance and two angles to the target. For example, inU.S. Pat. Nos. 7,196,302, 7,966,739 and 8,788,154, laser surveying andlaser measuring systems are described that utilize N-beams incombination with certain photo detection techniques to measurepositional data.

However, while the aforementioned systems provide highly accurateresults, the ability to utilize multiple, independent laser receivers tosimultaneously calculate positions remains a challenge. Accordingly,when locating points in a construction jobsite, it is typical for onlyone person to move the laser receiver from point to point. In order toensure that the laser receiver is placed in the correct location, theperson would typically have to work at least 5 minutes on ensuring thecorrect location.

Therefore, a need exists for a three dimensional (3D) measuring systemthat allows for the use of multiple, independent laser receivers tosimultaneously calculate positions without any need to communicate withthe laser transmitter. Furthermore it is desirable to have six degreesof freedom (“6DOF”) positions of multiple rigid objects, or of at leastone an element or physical feature in one object.

Certain positional tracking systems currently known in the art fully orpartially rely on tracking markers attached to objects, and then trackthe marked objects. In such systems, a tracked object typically must becovered with large tracking markers that can encode several bits ofdata, such that typically only large objects can be tracked.

Advances in computer vision algorithms have made it possible to do awaywith tracking markers in limited scenarios by using natural image/scenefeatures instead. Unfortunately, current tracking algorithms that relyon natural image features are typically not robust/precise enough towork consistently in many construction jobsite environments, which oftencontain transparent, shiny, and/or textureless objects. Extracting andidentifying natural features from images also tends to becomputationally expensive.

DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described, by way ofexample, with reference to the accompanying drawings, of which:

FIG. 1 is a perspective view of a first embodiment of the positionaltracking system;

FIG. 2 is a block diagram of the laser transmitter;

FIG. 3 is a block diagram of the layout indicator;

FIGS. 4A-4B are block diagrams of the control tracker, where FIG. 4A isa block diagram of the main components in the housing and FIG. 4B is ablock diagram of the main components in the base body;

FIG. 5 is a partial exploded view of components of a first embodiment ofthe control tracker;

FIG. 6 is a perspective view of a second embodiment of the positionaltracking system;

FIG. 7 is a front view of an embodiment of a layout indicator;

FIG. 8 is a partial exploded view of components of a second embodimentof the control tracker;

FIG. 9 is a partial cross-sectional view of components of the secondembodiment of the control tracker;

FIGS. 10A-10B illustrate components and outputs of the camera 308 in thesecond embodiment of the positional tracking system of FIG. 6, where thecamera is in a first orientation;

FIGS. 11A-11B illustrate components and outputs of the camera 308 in thesecond embodiment of the positional tracking system of FIG. 6, where thecamera is in a second orientation;

FIG. 12 illustrates an alternative component arrangement for camera 308in the second embodiment of the positional tracking system of FIG. 6;and

FIG. 13 illustrates another alternative component arrangement for camera308 in the second embodiment of the positional tracking system of FIG.6.

DETAILED DESCRIPTION

FIG. 1 shows a perspective view of a positional tracking system 100,which preferably includes a laser transmitter 110, a control tracker200, a layout indicator 300, and a local server 400 in communicationwith at least one of the laser transmitter 110, the control tracker 200,and/or the layout indicator 300. The local server 400 may be incommunication with a remote server or computing device 500 via acommunication network 450, such as the internet, the cellular network,etc.

Referring to FIG. 2, laser transmitter 110 may have a power supply 111,which accepts AC power or power from a power tool battery pack 150connected thereto, which supplies power to different components of lasertransmitter 110. Laser transmitter 110 may also include a controller112, a motor 115, a laser 114, a transceiver 116, all preferably poweredby power supply 111. Laser 114 shall emit a laser beam as discussed inmore detail below. Optics 114O may be disposed adjacent to laser 114 tomodify the emitted laser beam. Controller 112 may be connected to laser114 for controlling on-time and/or pulsing of laser 114.

Motor 115 may be connected to laser 114 and/or optics 114O for rotatingor oscillating the emitted laser beam. Preferably, the laser 114 and/oroptics 114O may be rotated at least 360 degrees so as to sweep theemitted laser beam around the jobsite, though persons skilled in the artwill recognize that the laser 114 and/or optics 114O may be rotatedthrough a smaller angle. Controller 112 may be connected to motor 115for controlling the speed and direction of the motor rotation, thuscontrolling the speed and direction of the moving laser beam.

Controller 112 may also be connected to a transceiver 116 for receivingand/or transmitting data and communication messages. Such data andcommunication messages may be sent or received via one or more of avariety of wireless technologies, including: wireless local area network(WLAN) technologies; wireless personal area network (WPAN) technologies(including low-rate wireless personal area network (LR-WPAN)technologies); radio frequency identification (RFID); ultra-wideband(UWB); ultrasound; sound; infrared; visible light; camera vision, etc.Included in WLAN technologies are those conforming to the Institute ofElectrical and Electronics Engineers (IEEE) 802.11 series of standards(e.g. Wi-Fi™). Included in WPAN and LR-WPAN technologies are thoseconforming to the IEEE 802.15 series of standards (e.g. Bluetooth™,ZigBee™, etc.).

At least one or more of the power supply 111, the power tool batterypack 150, the controller 112, the motor 115, the laser 114, and/or thetransceiver 116 are preferably disposed in a housing 117, which may befurther protected by a protective bar 118. Housing 117 may be disposedon a tripod 119.

Referring to FIGS. 1 and 4A, control tracker 200 may have a housing200H. Control tracker 200 may also have a power supply 201, whichaccepts power from a power tool battery pack 150 connected thereto,which supplies power to different components of control tracker 200.Control tracker 200 may also include a controller 202, a memory 203connected to controller 202, an inertial measurement unit (IMU) sensor204 providing information to controller 202, a display 205 connected tocontroller 202, a transceiver 206, and a laser assembly 207, allpreferably powered by power supply 201. Preferably display 205 is atouch-screen display that can display information as well as be used asan input interface, which is then sent to controller 202.

Multiple photo diodes PD1-PDN may be disposed on housing 200H,preferably on different faces and/or orientations of housing 200H. Suchphoto diodes PD1-PDN are preferably connected to controller 202 and canindicate when they have been lighted by a laser beam originating fromlaser transmitter 110.

Controller 202 may also be connected to the transceiver 206 forreceiving and/or transmitting data and communication messages. Such dataand communication messages may be sent or received via one or more of avariety of wireless technologies, including: wireless local area network(WLAN) technologies; wireless personal area network (WPAN) technologies(including low-rate wireless personal area network (LR-WPAN)technologies); radio frequency identification (RFID); ultra-wideband(UWB); ultrasound; sound; infrared; visible light; camera vision, etc.Included in WLAN technologies are those conforming to the Institute ofElectrical and Electronics Engineers (IEEE) 802.11 series of standards(e.g. Wi-Fi™). Included in WPAN and LR-WPAN technologies are thoseconforming to the IEEE 802.15 series of standards (e.g. Bluetooth™,ZigBee™, etc.).

Control tracker 200 preferably has laser assembly 207 for projecting alaser beam plane 200LP unto a surface S. A laser line 200LL is shown onthe surface S, where laser beam plane 200LP intersects surface S.Persons skilled in the art will recognize that laser beam plane 200LPcan be formed by projecting a laser beam through a curved lens (such asa cylindrical or partial cylindrical lens) or rotating a laser beam dot.

Referring to FIGS. 1 and 5, the housing 200H is disposed on a base 200Bthat can be affixed to the floor or an object. Base 200B may have a basebody 200BB and a mount body 200M disposed on base body 200BB. Mount body200M may have a bolt 200MB extending therefrom for threadingly engaginghousing 200H.

Preferably base body 200BB has a 3-2-1, or six-point, locational systemto fix the location of mount body 200M (and thus of housing 200H). Asseen in FIG. 5, the base body 200BB has a floor 200BF for supportingmount body 200M. Floor 200BF defines a substantially horizontal supportplane. Alternatively floor 200BF may have three support cones 200BP,providing three contact points for contacting mount body 200M anddefining a substantially horizontal support plane.

A wall 200BW preferably extends substantially perpendicular from floor200BF. Wall 200BW may have two support cones 200BP, providing twocontact points for contacting mount body 200M and restraining movementalong a first horizontal direction D1.

A second wall 200BS preferably extends substantially perpendicular bothfrom floor 200BF and wall 200BW. Wall 200BS may have one support cone200BP, providing one contact points for contacting mount body 200M andrestraining movement along a second horizontal direction D2substantially perpendicular to the first horizontal direction D1.

A third wall 200BSS may have a cam 200BC rotatably connected thereto,for providing one contact point for contacting mount body 200M andrestraining movement along the second horizontal direction D2.

With such arrangement, if mount body 200M (and/or housing 200H) ismoved, it can be easy relocated to the same position/location it wasbefore by placing mount body 200M against support cones 200BP and cam200BC.

FIGS. 8-9 show a second embodiment of the base 200B that can be affixedto the floor or an object. Base 200B may have a base body 200BB and amount body 200M disposed on base body 200BB. Base body 200BB may have apost 200BBP extending therefrom for engaging housing 200H. Preferablypost 200BBP extends through mount body 200M.

Base body 200BB may have a plurality of, and preferably at least three,channels 200V. Each channel 200V preferably has first and second ramps200VR1, 200VR2, for receiving semi-spherical contacts 200MS on mountbody 200M. Persons skilled in the art will recognize that eachsemi-spherical contact 200MS will preferably contact first and secondramps 200VR1, 200VR2 at two points. By providing three channels 200Vwith corresponding semi-spherical contact 200MS, it will be possible torepeatably locate mount body 200M relative to base body 200BB.

Housing 200H may be attached to mount body 200M and have an opening200HO for allowing post 200BBP therethrough. Post 200BBP may have aspherical or semi-spherical portion 200BBPS that engages a capturemechanism 200HC on housing 200H.

Capture mechanism 200HC preferably has at least one button 200HBextending out of housing 200H. Button 200HB may be connected a latchportion 200HBL which preferably contacts the underside of portion200BBPS. At least one spring 200HS may bias button 200HB (and/or latchportion 200HBL) towards a position where latch portion 200HBL contactsthe underside of portion 200BBPS.

Preferably latch portion 200HBL has a ramp 200HBLR contacting theunderside of portion 200BBPS. With such arrangement, as ramp 200HBLR ismoved towards portion 200BBPS, any play between housing 200H and basebody 200BB is reduced.

Persons skilled in the art will recognize that FIG. 9 shows two buttons200HB with corresponding latch portions 200HBL. Preferably buttons 200HBand corresponding latch portions 200HBL are connected by a correspondinglink 200HBLL. Springs 200HS are preferably disposed between one button200HB and the latch portion 200HBL corresponding to the other button200HB. With such arrangement, the user would preferably press bothbuttons 200HB separating latch portions 200HBL to create enough spacefor portion 200BPS to clear and move therethrough, in order to removehousing 200H from base body 200BB.

In order to place mount housing 200H on base body 200BB, the user wouldpreferably press both buttons 200HB separating latch portions 200HBL tocreate enough space for portion 200BPS to clear and move therethrough.When the housing 200H is disposed on base body 200BB, springs 200HSforce latch portions 200HBL (and thus ramps 200HBLR) against portion200BPS, taking up any play between housing 200H and base body 200BB.Persons skilled in the art will recognize that latch portions 200HBLwill each provide horizontal force vectors that would cancel out, aswell as vertical force vectors that would force housing 200H downwardlyagainst base body 200BB. Such mechanism allows a user to easily relocatehousing 200H to the same position/location it was before.

Referring to FIGS. 1, 4B and 5, base body 200BB may have a second powersupply 211, which accepts power from batteries 211B, which suppliespower to different components of base body 200BB. Base body 200BB mayalso include a controller 212, a memory 213 connected to controller 212,an inertial measurement unit (IMU) sensor 214 providing information tocontroller 212, and a transceiver 206. Persons skilled in the art shallrecognize that memory 213 may be non-volatile memory, such as flashmemory, EEPROM memory, a passive RFID tag containing a particular IDnumber, etc. Persons skilled in the art shall recognize that base body200BB may have a controller 212, a memory 213 connected to controller212, and a transceiver 206 incorporated as a RFID tag circuit. Personsskilled in the art should also recognize that other non-RFIDidentification methods, such as bar codes, QR codes, etc. can be used toprovide base body 200BB with a particular identification number.

Controller 212 may also be connected to the transceiver 216 forreceiving and/or transmitting data and communication messages. Such dataand communication messages may be sent or received via one or more of avariety of wireless technologies, including: wireless local area network(WLAN) technologies; wireless personal area network (WPAN) technologies(including low-rate wireless personal area network (LR-WPAN)technologies); radio frequency identification (RFID); ultra-wideband(UWB); ultrasound; sound; infrared; visible light; camera vision, etc.Included in WLAN technologies are those conforming to the Institute ofElectrical and Electronics Engineers (IEEE) 802.11 series of standards(e.g. Wi-Fi™). Included in WPAN and LR-WPAN technologies are thoseconforming to the IEEE 802.15 series of standards (e.g. Bluetooth™,ZigBee™, etc.).

Referring to FIGS. 1 and 3, layout indicator 300 may have a housing300H. Layout indicator 300 may also have a power supply 301, whichaccepts power from a power tool battery pack 150 connected thereto,which supplies power to different components of layout indicator 300.Layout indicator 300 may also include a controller 302, a memory 303connected to controller 302, an inertial measurement unit (IMU) sensor304 providing information to controller 302, a display 305 connected tocontroller 202, and a transceiver 306, all preferably powered by powersupply 301. Preferably display 305 is a touch-screen display that candisplay information as well as be used as an input interface, which isthen sent to controller 302.

Multiple photo diodes LPD1-LPDN may be disposed on housing 300H,preferably on different faces and/or orientations of housing 300H. Suchphoto diodes LPD1-LPDN are preferably connected to controller 302 andcan indicate when they have been lighted by a laser beam originatingfrom laser transmitter 110.

Housing 300H may also have a pole 300P with an end 300PE. Preferably end300PE has a conical tip ending in a point 300PEP. Pole 300P may beextendable by adding one or more extensions between housing 300H andpole 300P. Alternatively pole 300P may be telescoping.

Controller 302 may also be connected to the transceiver 306 forreceiving and/or transmitting data and communication messages. Such dataand communication messages may be sent or received via one or more of avariety of wireless technologies, including: wireless local area network(WLAN) technologies; wireless personal area network (WPAN) technologies(including low-rate wireless personal area network (LR-WPAN)technologies); radio frequency identification (RFID); ultra-wideband(UWB); ultrasound; sound; infrared; visible light; camera vision, etc.Included in WLAN technologies are those conforming to the Institute ofElectrical and Electronics Engineers (IEEE) 802.11 series of standards(e.g. Wi-Fi™). Included in WPAN and LR-WPAN technologies are thoseconforming to the IEEE 802.15 series of standards (e.g. Bluetooth™,ZigBee™, etc.).

Local server 400 may receive and/or transmit data and communicationmessages from and to the transceivers 116, 206, 306 laser transmitter110, the control tracker 200, and/or the layout indicator 300,respectively. Such data and communication messages may be sent orreceived via one or more of a variety of wireless technologies,including: wireless local area network (WLAN) technologies; wirelesspersonal area network (WPAN) technologies (including low-rate wirelesspersonal area network (LR-WPAN) technologies); radio frequencyidentification (RFID); ultra-wideband (UWB); ultrasound; sound;infrared; visible light; camera vision, etc. Included in WLANtechnologies are those conforming to the Institute of Electrical andElectronics Engineers (IEEE) 802.11 series of standards (e.g. Wi-Fi™).Included in WPAN and LR-WPAN technologies are those conforming to theIEEE 802.15 series of standards (e.g. Bluetooth™, ZigBee™, etc.).

Local server 400 is preferably connected to the internet 450 via atleast one of the following connections: digital subscriber lines (DSL),asymmetric digital subscriber lines (ADSL), symmetric digital subscriberlines (SDSL), very high digital subscriber lines (VDSL), cable-broadbandinternet connection, wireless broadband connection, T-1 lines, bondedT-1 lines, T-3 lines, optical carrier lines (OC3), internet oversatellite (IoS), etc.

Referring to FIGS. 1-2, laser transmitter 110 preferably projects V- orN-shaped beams, for example, which have a plurality of fan-shaped beamsin rotary irradiation at a constant speed in a well-known fashion.Persons skilled in the art are referred to US Publication Nos. US2017/0284790 and US 2016/0131761, and U.S. Pat. Nos. 7,196,302,7,966,739 and 8,788,154, which are fully incorporated herein byreference, for further information on positional tracking measuringsystem 100 and laser transmitter 110.

The laser transmitter 110 preferably projects beams so that thecross-section of the luminous fluxes of such beams is formed in a V- orN-shape, illustratively shown as vertical beam 130-3, vertical beam130-4 and beam 130-5 tilted at angle θ 165 on a diagonal line withrespect to vertical beam 130-3 and vertical beam 130-4. As will beappreciated, while the illustrative embodiments herein are describedusing N-shaped beams, including the addition of two additionalcoordinates within the N-beam system, it will be understood that anytype of laser beam that can be configured with the frequency or phasemodulation data as detailed herein can also be utilized. For example, ina non-N-beam system, an embodiment would provide only the azimuthalangle and distance.

Laser transmitter 110 may modulate beams 130-3, 130-4 (either usingpulse width modulation, frequency modulation or phase modulation, orother coding methodology) with data specifying an azimuth angleassociated with the current position of laser transmitter 110. Forexample, assuming a clockwise rotation of the beams 130-3, 130-4 with afirst position at 0 degrees, the on-time period of thepulse-width-modulated beams 130-3, 130-4 may be shorter when the beams130-3, 130-4 are at 10 degrees. Such on-time period would increase asthe beams 130-3, 130-4 rotated to the 20 degrees position, the 90degrees position, etc. Preferably, there is a linear correlation betweenthe on-time period and the angular position.

In this way, control tracker 200 and/or layout indicator 300, uponreceiving the transmitted modulated laser signal at photo diodesPD1-PDN, LPD1-LPDN will be able to directly estimate its azimuthalposition (i.e., an angle) by measuring the pulse width, the pulse widthfrequency or phase, as the case may be, of the modulated signal pulse.Further, in accordance with the embodiment, distance D3 (illustratively,the distance between laser transmitter 110 and layout indicator 300) canalso be determined at layout indicator 300 using the modulated signaland signal reflections between laser transmitter 110 and layoutindicator 300 (e.g., for long distances, one direct light pulse and onereflected light pulse is sufficient, and for short distances, two ormore reflected light pulses are typically generated in such aconfiguration) to calculate time-of-flight. Persons skilled in the artshall recognize that layout indicator 300 and/or laser transmitter 110preferably ensure that the light pulse has originated from the samelaser transmitter 110. This can be accomplished by layout indicator 300and/or laser transmitter 110 demodulating the information encoded in thelaser beam, which can be used to distinguish between laser beamsoriginating from multiple laser transmitters 110.

Persons skilled in the art will recognize that the height location ofcontrol tracker 200 and/or layout indicator 300 may be calculated byusing the time differential between when photo diodes LPD1-LPDN firstdetect vertical beam 130-4 and tilted beam 130-5 (or when tilted beam130-5 and vertical beam 130-6 are detected) to calculate the heightlocation. Alternatively, the height location can be determined byexamining the ratio between the measured separation of photo diodesLPD1-LPDN (due to the angular orientation of housing 300H) and theactual known separation of photo diodes LPD1-LPDN.

Because the distance D3, the height location and the angular positionrelative to laser transmitter 110 is known, it is possible to determinethe location of control tracker 200 and/or layout indicator 300 withCartesian coordinates. For example, by knowing the distance D3 and theazimuth angle relative to laser transmitter 110, the X- andY-coordinates of control tracker 200 and/or layout indicator 300 can becalculated by laser transmitter 110, control tracker 200 and/or layoutindicator 300. Furthermore, the height location would be theZ-coordinate.

Because layout indicator 300 would calculate height based on theposition of housing 300H, it is preferable laser transmitter 110 and/orlayout indicator 300 to also calculate the angle axis representations,quaternions, Euler angles or yaw/pitch/roll of housing 300H in order toknow the orientation of housing 300H relative to laser transmitter 110.This can be accomplished by noting which photo diodes LPD1-LPDN are hitby the different laser beams, and the order and timing of such hits (orby examining the ratio between the measured separation of photo diodesLPD1-LPDN (due to the angular orientation of housing 300H) and theactual known separation of photo diodes LPD1-LPDN). For example,assuming housing 300H is a cube, if the photo diodes disposed on thetop, front and left faces of the cube are hit by laser beams, but notthe back, rear and right faces, the orientation can be generallyestablished. By noting the order and timing in which the different photodiodes are hit by the laser beams, the exact angle axis representations,quaternions, Euler angles or yaw/pitch/roll of the cube can becalculated.

Once such calculations are completed, the exact orientation of housing300H is known. Because the length of pole 300P is known (and in the sameorientation as housing 300H), it is possible to calculate the X-, Y- andZ-coordinates of point 300PEP. Persons skilled in the art will recognizethat it is preferable to provide a means for calculating the length ofpole 300P when extended or adjusted and for transmitting suchinformation to the controller 302. For example, if extensions are used,controller 302 can receive a message from the extensions being used asto the number and length of each used extension, which is then added tothe length of pole 300P. If a telescoping pole 300P is adjusted, suchpole 300P may have an encoder to track the adjustment movements, whichare then used to calculate the length of pole 300P.

Persons skilled in the art will recognize that it is possible for layoutindicator 300 to calculate the length of pole 300P by placing the point300PEP on a fixed location, then rotating housing 300H about the point300PEP without moving point 300PEP. Controller 302 can calculate thedifferent positions and orientations of housing 300H and use thatinformation to resolve for the location of point 300PEP and distancefrom housing 300H. Persons skilled in the art will recognize that suchlocational calculations are preferably made by controllers 202, 302 ofcontrol tracker 200 and layout indicator 300, respectively. However, thecalculations may be conducted in local server 400 and/or lasertransmitter 110, as control tracker 200 and/or layout indicator 300 maytransmit the data and sensed information to local server 400 and/orlaser transmitter 110.

Persons skilled in the art that a junction can be disposed on pole 300Pand/or housing 300H to facilitate the disconnection and connectiontherebetween. For example, a user may remove a first pole 300P fromhousing 300H and install a second longer pole. Preferably, suchconnection will be a hot shoe/accessory shoe such as defined in ISO518:2006, allowing an electrical connection between pole 300P andhousing 300H.

Persons skilled in the art shall recognize that positional trackingsystem 100 can thus effectively calculate X-, Y- and Z-coordinates ofitems as well as their orientation (as represented by angle axisrepresentations, quaternions, Euler angles or yaw/pitch/roll). Thisallows the user to rotate the item along six degrees of freedom (6DoF)and have the positional tracking system 100 track it accordingly.

Because the positional tracking system 100 can calculate X-, Y- andZ-coordinates of items, it can be used to locate the items and/ordesired locations called for in building plans. Preferably the buildingplans are building information models (BIMs) specifying differentlocations for different features, parts, items, etc. For example, a BIMmodel may specify the locations where different anchors or outlets areto be placed at. Positional tracking system 100 can be used to easilyidentify and locate those locations.

In order to do so, it is necessary to correlate the BIM model to thephysical jobsite. The BIM model can be loaded unto the memories 203, 303of control tracker 200 and/or layout indicator 300, respectively, orinto local server 400, or a computing device 500 (which could be alaptop, smartphone or tablet). The user would identify two controlpoints in the BIM model that are in the area of the jobsite where thepositional tracking system 100 is to be used. These two or more controlpoints are typically on a floor. The user would put control tracker 200on the floor or wall (surfaces S) at a location corresponding to one ofthe control points, and orient the control tracker 200 so that laserline 200LL intersects the second control point.

Preferably, the BIM model (or a portion thereof) can be displayed on thedisplay 205, display 305, and/or displays of local server 400 and/orcomputing device 500. The user can select the first control point as thelocation of control tracker 200 and the second control point intersectedby laser line 200LL. The positional tracking system 100 can thencalculate the position and orientation of the control tracker 200relative to laser transmitter 110, and correlate the X-, Y- andZ-coordinates of the control tracker 200 to the BIM model.

Another method of correlating the BIM model to the actual physicaljobsite could be mounting control tracker 200 in a visible location,contacting one control point in the actual physical jobsite with point300PEP, selecting such point in the BIM model, then contacting anothercontrol point in the actual physical jobsite with point 300PEP, andselecting such point in the BIM model. By having at least two points inthe BIM model correlated with two known control points in the actualphysical jobsite, the entire BIM model is correlated to the actualphysical jobsite.

Once the control locations in the BIM model have been correlated tolocations in the actual physical jobsite, the user can easily locateother locations called for in the BIM model in the actual physicaljobsite. The user would upload a list of desired locations unto layoutindicator 300. The display 305 preferably shows the list of desiredlocations. The user would select a desired location. Because controller302 knows the X-Y- and Z-coordinates of point 300PEP as well as theorientation of housing 300H (and thus the orientation of display 305),it can calculate which direction the layout indicator 300 should bemoved to in order to move towards the desired location. Display 305 canshow the direction to move by showing arrows and providing an indicationas to when the desired location has been reached.

The user can then mark the desired location with spray paint or chalk.Persons skilled in the art shall recognize that pole 300P may have amarking device 300PM (such as a chalk tip, a grease pen, a marker, apunch, etc.) disposed in end 300PE to mark the desired position.

Persons skilled in the art will recognize that, because the locationalcalculations are preferably conducted by layout indicator 300, severallayout indicators 300 can be used at the same time. Therefore, multipleusers can be marking out desired locations at the same time. Thisprovides for substantial time savings compared with the prior artmethods.

Persons skilled in the art shall recognize that layout indicator(s) 300can send their location information to local server 400 (and thuscomputing device 500). Such information can be updated in real time.Preferably the location of layout indicator(s) 300 can be shown in a mapdisplayed by local server 400 and/or computing device 500. Local server400 and/or computing device 500 can store the movement path of thedifferent layout indicator(s) 300. Such movement paths can be analysedto determine whether the user of such particular layout indicator 300was being time-efficient in locating the different desired positions,etc.

Because positional tracking system 100 may be used over several days inthe same jobsite, it is preferable to attach base 200B to asemi-permanent position, so as to avoid having to conduct the entirecorrelation process of correlating the BIM model to the physical jobsitemultiple times. As mentioned above, control tracker 200 may have atleast one IMU sensor 204, 214 to sense when the control tracker 200 hasbeen bumped, moved, etc. If such movement has been detected, lasertransmitter 110, control tracker 200, layout indicator 300, local server400 and/or computing device 500 can provide or display an alert ornotification, notifying the user that the control tracker 200 should bereadjusted.

Because positional tracking system 100 may be used over several days inthe same jobsite, it is desirable for the base bodies 200BB of themultiple control trackers 200 to store an individual ID number (possiblya universally unique ID (UUID) number) for the corresponding base body200BB in the corresponding memory 213. This would allow the users tocollect housings 200H at the end of the work day, then dispose them onbase bodies 200BB on the next work day without having to use the samehousings 200H used on the previous work day. Control tracker 200 wouldjust check in the memory 213 for the ID number and correlate itsposition to the location noted for such base body 200BB in the BIM modelfile.

FIG. 6 shows a second embodiment of layout indicator 300, where likenumerals refer to like parts. The second embodiment of layout indicator300 differs from the first embodiment of layout indicator 300 asdiscussed below.

A retroreflective material, such as retroflective prism 307, ispreferably disposed on housing 300H. The retroreflective prism 307preferably reflects searching light and measuring light from a lasertransmitter 110 in the range of 360 degrees in a horizontal plane.Information on reflective prism 307 can be found in US PatentPublication Nos. 20160202058 (published on Jul. 14, 2016 and entitled“Surveying Instrument”) and 20150116693 (published on Apr. 30, 2015 andentitled “Three-Dimensional Measuring Method And Surveying System”),which are wholly incorporated by reference.

When laser transmitter 110 transmits the laser beam 130-7, it isreflected by prism 307 back to laser transmitter 110 as beam 130-8.Laser transmitter 110 reflects such beam back to layout indicator 300 asbeam 130-9. Beam 130-9 is then received by prism 307 and directedtowards photo diodes LPD1-LPDN. Persons skilled in the art shallrecognize that having the laser beam being reflected multiple timesfacilitates measuring the time of flight of the beam, which would beused in calculating distance D3.

In order to calculate azimuth angle, elevation and roll (or tilt angle),it is desirable to provide a camera 308 on layout indicator 300.Preferably camera 308 is a 360 degree camera that can capture images viaat least two or more camera inputs. As the laser transmitter 110 rotatesthe laser beam 130-7, at least one of the camera inputs will captureimages of the laser beam 130-7.

By combining the positional information of laser beam 130-7 within theimage field along with information from IMU sensor 304, the layoutindicator 300 can calculate the angle axis representations, quaternions,Euler angles or yaw/pitch/roll of housing 300H in order to know theorientation of housing 300H relative to laser transmitter 110. Personsskilled in the art are referred to US Publication No. US 2017/0284790,which are fully incorporated herein by reference, for furtherinformation on such calculations.

Such calculations can be facilitated by adding components to camera 308.Referring to FIGS. 10A-11B, camera 308 may have an image sensor 308Sdisposed between an upper photodiode 308UD and a lower photodiode 308LD.Preferably, the image sensor 308S, upper photodiode 308UD and lowerphotodiode 308LD are aligned in a line, preferably a vertical line, asshown in FIG. 10A.

With such arrangement, as laser beam 130-7 passes across camera 308, thedifferent components 130-3, 103-4, 130-5 of the laser beam 130-7 willpass across the image sensor 308S, upper photodiode 308UD and lowerphotodiode 308LD. As such components 130-3, 103-4, 130-5 pass across theimage sensor 308S, upper photodiode 308UD and lower photodiode 308LD,the image sensor 308S, upper photodiode 308UD and lower photodiode 308LDwill respectively output the image 308SO and the signals (graphedrelative to time) 308UDO, 308LDO.

Persons skilled in the art will recognize that, due to the relativebrightness of the laser 130-7, the image 308SO captured image sensor308S would typically show only as a dot (or pixel(s)) within the imagefield of image 308SO. The distance of the dot from the vertical (left,right) edges can be used to determine the yaw angle, i.e., the anglebetween the transmitter 110 and laser receiver 300 along a horizontalplane. Alternatively, the horizontal distance of the dot from a centerpoint can also be used to determine the yaw angle. Similarly, thedistance of the dot from the horizontal (top, bottom) edges can be usedto determine the pitch angle, i.e., the angle between the transmitter110 and laser receiver 300 along a vertical plane. Alternatively, thevertical distance of the dot from a center point can also be used todetermine the pitch angle.

The tilt angle (or roll) of laser receiver 300 relative to transmitter110 can be calculated by using the information received from the upperand lower photodiodes 308UD, 308LD. For example, if the upper and lowerphotodiodes 308UD, 308LD are aligned in a vertical line (as shown inFIG. 10A), the outputs 308UDO, 308LDO will be relatively similar (asshown in FIG. 10B), as the laser beam 103-7 will hit upper and lowerphotodiodes 308UD, 308LD at the same time. However, if the upper andlower photodiodes 308UD, 308LD are aligned in an inclined line (as shownin FIG. 11A), the outputs 308UDO, 308LDO will not be aligned. As shownin FIG. 11B, the laser beam 103-7 would hit upper photodiode 308UDfirst, then lower photodiode 308LD later. The system can use the timedifferential between the detected hits to calculate the tilt angle (orroll) of the laser receiver 300 relative to transmitter 110.

FIG. 12 shows an alternative component arrangement for camera 308, wherelike numerals refer to like parts. As before, laser beam 103-7 isrotated across camera 308. Laser beam 103-7 may be projected through animage divider 308ID. Part of the beam is reflected into an image sensor308DS. As before, image sensor 308DS will generate an image (not shown)with a dot, which can be used to calculate the yaw and pitch angles.

Another part of the beam is preferably projected unto a projectionscreen 308PS. The beam will show as a line 308PSI on projection screen308PS. Such image is captured by image sensor 308S. Unlike the imagecaptured by image sensor 308DS, the image captured by image sensor 308Swill show a line in the image field. The tilt angle (or roll) of thelaser receiver 300 relative to transmitter 110 can be calculated bydetermining the angle of the line image relative to the image field.

FIG. 13 illustrates another alternative component arrangement for camera308, where like numerals refer to like parts. In this embodiment, adiffraction grating 308DG is disposed in front of projection screen308PS. The diffraction grating 308DG basically splits the laser beam103-7 into multiple parallel lines, which are projected unto projectionscreen 308PS and captured by image sensor 308S.

As in the previous embodiment, the tilt angle (or roll) of the laserreceiver 300 relative to transmitter 110 can be calculated bydetermining the angle of the line image(s) relative to the image field.Furthermore, the yaw angle can be determined by calculating the distancebetween the vertical line images. In addition, if the laser beam(s)103-7 and 103-8, or 103-8 and 103-9 are sent through a double-axisdiffraction grating, the system can calculate the yaw and pitch anglesby calculating the distance between the vertical and horizontal lineimages, respectively. Persons skilled in the art will note that thesystem may check whether the spacing between vertical (or horizontal)line images is the same or variable, as identical spacing would indicatea 0° angle, whereas variable spacing would indicate an angle that can becalculated by comparing the spacing between several lines.

FIG. 7 shows a third embodiment of layout indicator 300, where likenumerals refer to like parts. The third embodiment of layout indicator300 differs from the first and second embodiments of layout indicator300 as discussed below. Layout indicator 300 may have multiple prisms307 (with corresponding photo diodes LPD1-LPD) on housing 300H and/orpole 300P. The information gathered from the multiple photo diodes canbe used to calculate the distance from laser transmitter 110, location,elevation, angle axis representations, quaternions, Euler angles oryaw/pitch/roll of housing 300H.

Persons skilled in the art will also recognize that control tracker 200may also be provided with at least one retroreflective prism 200P(similar to prism 307) and corresponding photo diodes (not shown butsimilar to photo diodes LPD1-LPD in layout indicator 300 shown in FIG.6). The information gathered from the multiple photo diodes can be usedto calculate the distance from laser transmitter 110, location,elevation, angle axis representations, quaternions, Euler angles oryaw/pitch/roll of housing 200H.

It will be understood that the above description and the drawings areexamples of particular implementations of the invention, but that otherimplementations of the invention are included in the scope of theclaims.

What is claimed is:
 1. A position tracking system comprising: a lasertransmitter comprising a laser for emitting a laser beam, a controllercontrolling the laser, and a motor for rotating the emitted laser beam,a control tracker comprising a housing, a power supply disposed withinthe housing that accepts power from a power tool battery pack connectedthereto, a controller disposed within the housing, a memory connected tothe controller, an inertial measurement unit (IMU) sensor providinginformation to the controller, a transceiver disposed within thehousing, at least two photo diodes disposed on the housing, and a laserassembly for generating a beam to be projected unto a surface, a layoutindicator comprising a housing, a controller disposed within thehousing, a memory connected to the controller, an inertial measurementunit (IMU) sensor providing information to the controller, a transceiverdisposed within the housing, at least two photo diodes disposed on thehousing, and a laser assembly, a local server in communication with atleast one of the laser transmitter, the control tracker and the layoutindicator.
 2. The position tracking system of claim 1, wherein thelayout indicator comprises a pole connected to the housing.
 3. Theposition tracking system of claim 2, wherein the pole has an end.
 4. Theposition tracking system of claim 3, wherein the end has a conical tip.5. The position tracking system of claim 1, wherein the lasertransmitter projects V- or N-shaped beams.
 6. The position trackingsystem of claim 5, wherein at least one portion of the beams ismodulated with azimuth angle data.
 7. The position tracking system ofclaim 6, wherein the at least one portion of the beam is modulated usingpulse width modulation, frequency modulation or phase modulation.